// mtrand.h
// C++ include file for MT19937, with initialization improved 2002/1/26.
// Coded by Takuji Nishimura and Makoto Matsumoto.
// Ported to C++ by Jasper Bedaux 2003/1/1 (see http://www.bedaux.net/mtrand/).
// The generators returning floating point numbers are based on
// a version by Isaku Wada, 2002/01/09
//
// Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// 3. The names of its contributors may not be used to endorse or promote
//    products derived from this software without specific prior written
//    permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Any feedback is very welcome.
// http://www.math.keio.ac.jp/matumoto/emt.html
// email: matumoto@math.keio.ac.jp
//
// Feedback about the C++ port should be sent to Jasper Bedaux,
// see http://www.bedaux.net/mtrand/ for e-mail address and info.

#ifndef MTRAND_H
#define MTRAND_H

class MTRand_int32 //Mersenne Twister random number generator
{
public:
	//default constructor: uses default seed only if this is the first instance
	MTRand_int32()
	{
		if (!init)
		{
			seed(5489UL);
			init = true;
		}
	}

	//constructor with 32 bit int as seed
	MTRand_int32(unsigned long s)
	{
		seed(s);
		init = true; 
	}

	//constructor with array of size 32 bit ints as seed
	MTRand_int32(const unsigned long* array, int size)
	{
		seed(array, size);
		init = true;
	}

	//the two seed functions
	void seed(unsigned long);                  //seed with 32 bit integer
	void seed(const unsigned long*, int size); //seed with array

	//overload operator() to make this a generator (functor)
	unsigned long operator()()
	{
		return rand_int32();
	}

	//2007-02-11: made the destructor virtual; thanks "double more" for pointing this out
	virtual ~MTRand_int32() {}  //destructor

protected: //used by derived classes, otherwise not accessible; use the ()-operator
	unsigned long rand_int32(); //generate 32 bit random integer

private:
	static const int n = 624, m = 397; //compile time constants

	//the variables below are static (no duplicates can exist)
	static unsigned long state[n];     //state vector array
	static int p;                      //position in state array
	static bool init;                  //true if init function is called

	//private functions used to generate the pseudo random numbers
	unsigned long twiddle(unsigned long, unsigned long); //used by gen_state()
	void gen_state();                                    //generate new state

	//make copy constructor and assignment operator unavailable, they don't make sense
	MTRand_int32(const MTRand_int32&);   //copy constructor not defined
	void operator=(const MTRand_int32&); //assignment operator not defined
};

//inline for speed, must therefore reside in header file
inline unsigned long MTRand_int32::twiddle(unsigned long u, unsigned long v)
{
	return (((u & 0x80000000UL) | (v & 0x7FFFFFFFUL)) >> 1)
		^ ((v & 1UL) ? 0x9908B0DFUL : 0x0UL);
}

inline unsigned long MTRand_int32::rand_int32() //generate 32 bit random int
{
	if (p == n) gen_state(); //new state vector needed

	//gen_state() is split off to be non-inline, because it is only called once in
	//	every 624 calls and otherwise irand() would become too big to get inlined
	unsigned long x = state[p++];
	x ^= (x >> 11);
	x ^= (x << 7) & 0x9D2C5680UL;
	x ^= (x << 15) & 0xEFC60000UL;

	return x ^ (x >> 18);
}

//generates double floating point numbers in the half-open interval [0, 1)
class MTRand : public MTRand_int32
{
public:
	MTRand() : MTRand_int32() {}
	MTRand(unsigned long s) : MTRand_int32(s) {}
	MTRand(const unsigned long* s, int size) : MTRand_int32(s, size) {}
	~MTRand() {}

	double operator()()
	{
		return static_cast<double>(rand_int32()) * (1. / 4294967296.); //divided by 2^32
	}

private:
	MTRand(const MTRand&);           //copy constructor not defined
	void operator = (const MTRand&); //assignment operator not defined
};

//generates double floating point numbers in the closed interval [0, 1]
class MTRand_closed : public MTRand_int32
{
public:
	MTRand_closed() : MTRand_int32() {}
	MTRand_closed(unsigned long s) : MTRand_int32(s) {}
	MTRand_closed(const unsigned long* s, int size) : MTRand_int32(s, size) {}
	~MTRand_closed() {}

	double operator()()
	{
		return static_cast<double>(rand_int32()) * (1. / 4294967295.); //divided by 2^32 - 1
	}

private:
	MTRand_closed(const MTRand_closed&);    //copy constructor not defined
	void operator = (const MTRand_closed&); //assignment operator not defined
};

//generates double floating point numbers in the open interval (0, 1)
class MTRand_open : public MTRand_int32
{
public:
	MTRand_open() : MTRand_int32() {}
	MTRand_open(unsigned long s) : MTRand_int32(s) {}
	MTRand_open(const unsigned long* s, int size) : MTRand_int32(s, size) {}
	~MTRand_open() {}

	double operator()()
	{
		return (static_cast<double>(rand_int32()) + .5) * (1. / 4294967296.); //divided by 2^32
	}

private:
	MTRand_open(const MTRand_open&);      //copy constructor not defined
	void operator = (const MTRand_open&); //assignment operator not defined
};

//generates 53 bit resolution doubles in the half-open interval [0, 1)
class MTRand53 : public MTRand_int32
{
public:
	MTRand53() : MTRand_int32() {}
	MTRand53(unsigned long s) : MTRand_int32(s) {}
	MTRand53(const unsigned long* s, int size) : MTRand_int32(s, size) {}
	~MTRand53() {}

	double operator()()
	{
		return (static_cast<double>(rand_int32() >> 5) * 67108864. + 
			static_cast<double>(rand_int32() >> 6)) * (1. / 9007199254740992.);
	}

private:
	MTRand53(const MTRand53&);         //copy constructor not defined
	void operator = (const MTRand53&); //assignment operator not defined
};

#endif //MTRAND_H
